unix4lyfe git - darkstat/blob - localip.c

   1 /* darkstat 3
   2  * copyright (c) 2001-2008 Emil Mikulic.
   3  *
   4  * localip.c: determine local IP of our capture interface
   5  *
   6  * You may use, modify and redistribute this file under the terms of the
   7  * GNU General Public License version 2. (see COPYING.GPL)
   8  */
   9
  10 #include "darkstat.h"
  11 #include "addr.h"
  12 #include "conv.h" /* for strlcpy */
  13 #include "err.h"
  14 #include "localip.h"
  15
  16 #include <sys/types.h> /* OpenBSD needs this */
  17 #include <sys/socket.h>
  18 #include <net/if.h>
  19 #include <ifaddrs.h>
  20 #include <errno.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23
  24 static const char *iface = NULL;
  25 struct addr localip4, localip6;
  26 static struct addr last_localip4, last_localip6;
  27
  28 void
  29 localip_init(const char *interface)
  30 {
  31    iface = interface;
  32    localip_update();
  33 }
  34
  35 void
  36 localip_update(void)
  37 {
  38    struct ifaddrs *ifas, *ifa;
  39    int got_v4 = 0, got_v6 = 0;
  40
  41    localip4.family = IPv4;
  42    localip6.family = IPv6;
  43
  44    if (iface == NULL) {
  45       /* reading from capfile */
  46       localip4.ip.v4 = 0;
  47       memset(&(localip6.ip.v6), 0, sizeof(localip6.ip.v6));
  48       return;
  49    }
  50
  51    if (getifaddrs(&ifas) < 0)
  52       err(1, "can't get own IP address on interface \"%s\"", iface);
  53
  54    for (ifa = ifas; ifa; ifa = ifa->ifa_next) {
  55       if (got_v4 && got_v6)
  56          break;   /* Task is already complete. */
  57
  58       if (strncmp(ifa->ifa_name, iface, IFNAMSIZ))
  59          continue;   /* Wrong interface. */
  60
  61       /* The first IPv4 name is always functional. */
  62       if ((ifa->ifa_addr->sa_family == AF_INET) && !got_v4)
  63       {
  64          /* Good IPv4 address. */
  65          localip4.ip.v4 =
  66             ((struct sockaddr_in *)ifa->ifa_addr)->sin_addr.s_addr;
  67          got_v4 = 1;
  68          continue;
  69       }
  70
  71       /* IPv6 needs some obvious exceptions. */
  72       if ( ifa->ifa_addr->sa_family == AF_INET6 ) {
  73          struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) ifa->ifa_addr;
  74
  75          if ( IN6_IS_ADDR_LINKLOCAL(&(sa6->sin6_addr))
  76               || IN6_IS_ADDR_SITELOCAL(&(sa6->sin6_addr)) )
  77             continue;
  78
  79          /* Only standard IPv6 can reach this point. */
  80          memcpy(&(localip6.ip.v6), &sa6->sin6_addr, sizeof(localip6.ip.v6));
  81          got_v6 = 1;
  82       }
  83    }
  84
  85    freeifaddrs(ifas);
  86
  87    /* Report an error if IPv4 address could not be found. */
  88    if (!got_v4)
  89        err(1, "can't get own IPv4 address on interface \"%s\"", iface);
  90
  91    if (!addr_equal(&last_localip4, &localip4)) {
  92       verbosef("localip4 update(%s) = %s", iface, addr_to_str(&localip4));
  93       last_localip4 = localip4;
  94    }
  95    if (!addr_equal(&last_localip6, &localip6)) {
  96       verbosef("localip6 update(%s) = %s", iface, addr_to_str(&localip6));
  97       last_localip6 = localip6;
  98    }
  99 }
 100
 101 /* vim:set ts=3 sw=3 tw=78 expandtab: */